In general, it is known that a substance undergoes thermal expansion with increasing temperature. Accordingly, there may occur various problems with parts to be used in devices that are exposed to temperature change.
Accordingly, various methods for inhibition of thermal expansion at different temperatures have heretofore been investigated. For example, JP-A 2003-146693 describes use of ceramics or glass ceramics having a negative coefficient of linear thermal expansion of from −1×10−6/° C. to −12×10−6/° C. in a temperature range of −40° C. to 100° C. As examples of such ceramics or glass ceramics, it shows ceramics or glass ceramics that comprise a β-quartz solid solution or a β-eucryptite solid solution as the main crystal thereof, or polycrystalline ceramics that comprise a phosphate tungstate or a tungstate containing at least any of Zr and Hf as the main crystal thereof.
In their practical use, however, they require various conditions and could not be a satisfactory thermal expansion inhibitor.
It has heretofore been known that a perovskite manganese nitride having a chemical formula Mn3XN (wherein X represents Ni, Zn, Ga or Ag) exhibits a phenomenon of such that the lattice in the low-temperature magnetic ordered phase expands with the formation of an antiferromagnetic order therein (magnetovolume effect) (J. P. Bouchaud et al., C.R. Acad. Sc. Paris C 262, 640 (1966); J. P. Bouchaud, Ann. Chim. 3, 81 (1968); D. Fruchart et al., Solid State Commun. 9, 1793 (1971); R. Fruchart et al., J. Phys. (Paris) 32, C1-982 (1971); D. Fruchart et al., Proc. Intern. Conf. Magn. 4, 572 (1974); Ph. l'Heritier et al., Mat. Res. Bull. 14, 1089 (1979); Ph. l'Heritier et al., Mat. Res. Bull. 14, 1203 (1979); W. S. Kim et al., Phys. Rev. B 68, 172402 (2003)). However, this phenomenon is a sharp first-order phase transition, and the transition width is within 1° C. and is narrow, and therefore the substance could not be put in practical use as an industrial thermal expansion inhibitor.